Regarding a so-called life cycle from manufacture of an item through to final obsolescence, various techniques have been proposed to obtain information about the operating condition and history of the item and manage the item by referring to such information.
For instance, Japanese Laid-Open Patent Application No. H10-222568 discloses the following system to reduce the cost of the entire life cycle. Identification information such as model and production numbers, material information, operation information, error information, and maintenance information are recorded for each product and component, at each stage such as manufacture, use, and maintenance. The recorded information is read and put to use for evaluating the product in each of the stages including manufacture, maintenance, collection, and resale.
Also, Japanese Laid-Open Patent Application No. H11-120308 discloses a historical information storing device which attaches historical information of a product to the product itself.
According to these conventional techniques, information relating to a product can be attached to the product and passed through each stage of the life cycle together with the product. This allows the information relating to the product to be shared and freely used at any stage of the life cycle such as manufacture, maintenance, collection, and resale. However, when the information attached to the product is such available to any person, secret information cannot be attached to the product. This is one of the main reasons why the technique of distributing the product and the information relating to the product together in the life cycle has not been so widely used.
To solve the above problem, the present invention aims to provide an information recording medium and contactless IC tag that can store secret information for each stage, when the information recording medium or the contactless IC tag is attached to an item which passes through multiple stages. The invention also aims to provide an access device that is capable of reading/writing information from/to the contactless IC tag in secrecy for each stage, an access system made up of the contactless IC tag and the access device, and a life cycle management system made up of the contactless IC tag and the access devices provided for the multiple stages. The invention further aims to provide an input/output method used for the contactless IC tag, and an access method used for the access device.